Freezer failure cited in loss of McLean tissue samples

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An independent analysis has faulted a freezer’s digital controls for the loss of 147 brain samples that defrosted earlier this year at the Harvard-affiliated Brain Tissue Resource Center at McLean Hospital.

Among those samples were the brains of 54 people who had autism – nearly a quarter of the autism brain samples available for research into a condition that now affects 1 in 88 American children. At the time researchers said the collection, which took 14 years to amass, could set autism research back perhaps as long as a decade.

McLean staff discovered on May 31 that Freezer U — one of 24 in its brain bank — had lost power days earlier. No one noticed because the digital readout on the front of the freezer still indicated minus 79 degrees, the appropriate temperature. A backup system designed to detect freezer malfunctions also failed.

This summer, McLean hired LWG Consulting, an Illinois-based company which specializes in equipment loss and forensic engineering, to investigate the failure. In a three-paragraph statement to be released Monday, McLean said LWG had attributed the failure to the freezer’s microprocessor-based digital controls.

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In the statement, McLean reiterated its commitment to ensuring the safety of its facility, “the largest and longest-operating federally funded” brain bank in the country. “All freezers, including their microprocessors, have undergone a thorough inspection and the hospital is in the process of installing a third alarm that will serve as a tertiary backup to two other alarm systems already in place and will further ensure that laboratory personnel will be notified immediately if any freezer begins to show a warming of its internal temperature.”

The company that made the $12,000 freezer, Thermo Fisher Scientific, whose US headquarters is in Waltham, released this statement in response to inquiries from the Globe: “We share the concerns of McLean Hospital and the entire scientific community over the loss of research material. In our investigation into this incident, we were unable to replicate the freezer malfunction. Given the sensitive nature of material frequently stored in laboratory freezers, we reiterate McLean’s emphasis on the importance of backup alarm systems, which we recommend to our customers.”

At least one leading autism researcher, Manuel Casanova of the University of Louisville, found the investigation and McLean’s conclusions unsatisfactory.

So many autism brain samples should not have been stored in one freezer, Casanova said. The brains had been consolidated into Freezer U several weeks before the failure to make them easier to access for visiting researchers. McLean staff said earlier this year that they had not yet had time to redistribute the brains among the 24 freezers, as is their standard operating procedure.

“Shifting a significant number of brains to a single freezer and leaving them there for a prolonged period of time contravenes a safety norm of brain banks,” Casanova said. “It stands to common reasoning that you try to minimize damage in case of a freezer meltdown by distributing brains with similar diagnosis among many freezers.”

He also faulted brain bank officials for not opening the freezer doors more often, to check the temperature themselves.

“McLean can also institute as many alarms as they desire, but occasionally they should also look, visually, into the freezers,” he said.

H. Ronald Zielke, director of the Eunice Kennedy Shriver NICHD Brain and Tissue Bank for Developmental Disorders at the University of Maryland, defended McLean’s actions. Sometimes freezers just fail, he said, and there was nothing McLean officials could have done to prevent the loss.

The Belmont brain bank “has done an outstanding job in collecting and distributing tissue for research on many disorders over the last few decades,” he wrote in an e-mail. “Mechanical failures are always possible. It is a dread that hangs over the head of anyone responsible for storing tissue for decades.”

Frozen brain tissue offers the only means for examining the proteins in the deceased person’s brain, as well as the microscopic structure of brain tissue and other biological markers that researchers may want to investigate.

Understanding the tissue structure and the activities of the proteins could offer crucial insights into a condition that largely remains a mystery.

The lost autism brains make up about one-third of the Autism Tissue Program, which is run by the advocacy group Autism Speaks, and is by far the largest collection in the world. Zielke’s brain bank has the second-largest collection, with about 60 brains. Other collections are much smaller, autism researchers said.

Robert Ring, Autism Speaks’ vice president of translational research, said in a statement that his organization is satisfied with McLean’s investigation, its response to the freezer failure, and the safeguards it had in place before the incident. For many of the samples, half the brain had been stored in formaldehyde, so some genetic and other analysis is still possible, he wrote.

“The event has also placed a new urgency on outreach efforts to increase awareness for the important role that donation plays in supporting research that has the ability to fundamentally change our understanding of the biological causes of autism and other disorders of the nervous system,” he said in the statement.

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